Ozone Hole
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Just when you thought the ozone hole was gone there it is again, like the unwanted guest who just doesn't know when to leave. And its not like it isnt getting the hint. Hi I'm Dave Thurlow for the Weather Notebook.

What appeared to be realistic solution to the ozone holes unwanted growth took place in 1987 when the whole world agreed to the Montreal Protocol, a measure to eliminate ozone-eating emissions. Since then, we've pretty much stopped making these chemical catalysts that reduce ozone in the stratosphere. But, in September NASA reported that the ozone hole above the Antarctic had grown to its largest level ever--three times as big as the United States. Why is it taking such a very long time for it leave?

The reason is that the chemicals at fault-CFCs theyre called-are almost indestructible. Their stability is what made them so useful for various technologies in the first place. Once CFCs get into the air, the wind sifts them across the entire global atmosphere. It takes years for CFCs to make it up into the stratosphere to destroy ozone. Only ultraviolet light can break up CFCs for good, and that light is only strong enough in the stratosphere. This means it could be another 50 years before the ozone hole goes away for good.

The ozone whole may have warn out its welcome, but unfortunately it has nowhere to go. All we can do is keep a sharp but distant eye on its regrettable behavior.

Bob Henson contributed to todays show. Hes a meteorologist in Boulder Colorado. The weather Notebook is a production of the Mount Washington Observatory, which you can find out about at mountwashington.org